The 405 Freeway looking south from the Fairview Road bridge in Costa Mesa. Over the next five years, the 18 freeway bridges between the 73 and the 605 will be widened, starting Tuesday, Aug. 7. (Photo by Jeff Gritchen, Orange County Register/SCNG)

It’s time to start paying attention to the 405 Freeway widening project – and to figure out alternate routes.

Beginning next week, bridges crossing over the freeway will lose lanes or – in some cases – be shut down altogether. Construction work, however, will be staggered along the 16-mile stretch to help alleviate traffic jams sure to plague each area as it takes its turn.

The first of 18 bridges set for reconstruction is the McFadden Avenue bridge edging Westminster and Huntington Beach. It will fully close at 10 p.m. Tuesday, Aug. 7, remaining off-limits for at least a year, Orange County Transportation Authority spokesman Joel Zlotnik said.

Over the next five years, 18 bridges across the 405 Freeway will be under construction on staggered dates, starting with McFadden on Aug. 12. This map shows the year construction will begin for each bridge, and whether the bridge will be completely closed or torn down in phases. (Map courtesy of Orange County Transportation Authority)

The 405 Freeway looking south from the Fairview Road bridge in Costa Mesa. Over the next five years, the 18 freeway bridges between the 73 and the 605 will be widened, starting Tuesday, Aug. 7. (Photo by Jeff Gritchen, Orange County Register/SCNG)

At sundown on Aug. 18 and, again, Aug. 25, the bridge will undergo a two-part demolition, requiring total freeway closures in both directions from 10 p.m. to 7 a.m., Zlotnik said. Drivers will be routed off the freeway at the ramp before McFadden Avenue and back on at the next ramp. If driving northbound, that’s Beach Boulevard and then Bolsa Avenue; vice-versa heading southbound.

Other bridges with higher traffic volumes will be handled in two stages rather than demolished all at once, a process that will take about 18 months.

In those cases, only half of the bridge will be dismantled and traffic will be moved to the remaining side. Eventually, traffic will shift to the completed side and the second half of the bridge will be bulldozed and rebuilt.

Next up on the timeline after McFadden Avenue is the Slater Avenue bridge in Fountain Valley, where construction should get underway by the end of the year, Zlotnik said. Unlike McFadden, it will remain in use, one side at a time.

In addition to McFadden, bridges scheduled to be wholly out of commission during demolition and construction are Bushard Street and Talbert Avenue in 2019, Newland Street and Ward Street in 2020 and Edinger Avenue in 2021.

While several bridges may be worked on simultaneously, no adjacent bridges will be closed at the same time, Zlotnik said.

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Westminster, home to 10 freeway bridges, will be most impacted by the five-year project. In addition to Huntington Beach, other affected cities bordering the 405 are Long Beach, Seal Beach, Rossmoor, Garden Grove, Fountain Valley and Costa Mesa.

Less intrusive tasks – such as tree trimming, overnight striping and erecting concrete barriers – began in January.

The I-405 Improvement Project aims to ease congestion as Southern California’s population increases. According to the OCTA, traffic on the already congested 405 will grow 35 percent by 2040.

Of the project’s $1.9 billion total price tag, about $1.1 billion will come from Measure M, the county’s half-cent sales tax for transportation improvements. The federal government will cover $45.6 million, and the state $89.7 million.

A low-interest loan for $629 million will be paid off by revenue from pay-to-use lanes.

Ultimately, the end product will feature two new lanes in each direction – increasing capacity from five to seven lanes.

The existing carpool lane on each side will become one of two “express lanes” – still free for vehicles carrying three or more people. Solo drivers will pay a fee for the lanes, as will cars with two people during rush hour.

Express lane users will need a transponder that will automatically deduct fees. The price will range from $10 at rush hour to 50 cents at nighttime, Zlotnik said.

Officials estimate that those driving the entire stretch will halve the rush-hour journey to 30 minutes, with people who pay to enter the express lanes making the trip in about 15 minutes.

OCTA will host informational meetings for residents living near the construction before beginning work on each bridge. McFadden Avenue workshops will be held in Westminster on Saturday, Aug. 4, at 9 a.m. at College Park, 15422 Vermont St., and 11 a.m. at John F. Land School, 15151 Temple St.

After majoring in journalism at the University of Texas, Susan Christian Goulding got her start as a copy editor and reporter at the (late, great) Los Angeles Herald Examiner. She then worked at the (late, great) Santa Monica Outlook and the Daily Breeze as a features editor, writer and columnist. She moved to the Orange County bureau of the Los Angeles Times as a features and business writer. After that five-year stint, she worked as a correspondent for People magazine and a regular freelancer for Readers Digest while raising her two kids, Erin and Matt. During this time, she also wrote a weekly column for the Daily Breeze. Next, she gave up all possibility of free time and earned a teaching credential and masters at UCI. She taught English for four often rewarding and always challenging years in Compton, then at LMU and El Camino College. Missing journalism, Goulding circled back to her original career last year, joining the Orange County Register as a reporter. She also enjoys her return to column writing for the newspaper's OC Home magazine.